Summary of Transactions in the ALLL by Portfolio segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Beginning Balance	$ 1,735		$ 2,016	$ 1,854	[1]	$ 2,255
Losses charged off	(141)		(188)	(454)		(660)
Recoveries of losses previously charged off	(32)		(32)	(101)		(103)
Provision for loan and lease losses	51		65	176		227
Ending Balance	1,677	[1]	1,925	1,677	[1]	1,925
Commercial Portfolio Segment
Beginning Balance	1,183		1,347	1,236	[2]	1,527
Losses charged off	(61)		(76)	(189)		(289)
Recoveries of losses previously charged off	(17)		(14)	(46)		(47)
Provision for loan and lease losses	8		2	54		2
Ending Balance	1,147	[3]	1,287	1,147	[3]	1,287
Residential Mortgage Loans
Beginning Balance	201		232	229	[2]	227
Losses charged off	(15)		(28)	(55)		(104)
Recoveries of losses previously charged off	(3)		(2)	(8)		(5)
Provision for loan and lease losses	5		26	12		104
Ending Balance	194	[3]	232	194	[3]	232
Consumer Portfolio Segment
Beginning Balance	247		316	278	[2]	365
Losses charged off	(65)		(84)	(210)		(267)
Recoveries of losses previously charged off	(12)		(16)	(47)		(51)
Provision for loan and lease losses	41		42	120		141
Ending Balance	235	[3]	290	235	[3]	290
Unallocated
Beginning Balance	104		121	111	[2]	136
Provision for loan and lease losses	(3)		(5)	(10)		(20)
Ending Balance	$ 101	[3]	$ 116	$ 101	[3]	$ 116

[1] Includes $53 and $0 of cash and due from banks, $50 and $50 of commercial mortgage loans, $1,145 and $0 of automobile loans, $(16) and $(5) of ALLL, $12 and $3 of other assets, $2 and $0 of other liabilities, and $1,198 and $0 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2013 and December 31, 2012, respectively. See Note 9.

[2] Includes $11 related to leveraged leases.

[3] Includes $10 related to leveraged leases.